In this section, we summarise the creation of the input lists of objects that were processed by our pipeline. Gaia DR3 will release a probabilistic classification of the sources into five classes: star, galaxy, quasar, binary star, or white dwarf [1]}. Nevertheless, due to the complex and long processing plan within the Gaia DPAC, we were not able to benefit from this classification before publication of the present paper. Indeed, we had to set up input lists of sources using surveys and literature studies as of early 2018.
The list of quasars was set up by compiling major AGN and quasars catalogues. The list of galaxies was established from a previous paper [2]} classifying sources from the Gaia DR2 catalogue with entry in the allWISE catalogue [3]} into point-like or extended sources. Due to long processing cycles within DPAC, these input lists had to be delivered by early 2018, preventing the inclusion of more recent catalogues in our compilation of quasars.
